501  
FGUS73 KFSD 221513  
ESFFSD  
SDC005-011-027-035-061-067-079-083-087-099-101-111-125-127-135-  
MNC033-063-081-083-101-105-117-133-NEC013-014-  
IAC021-035-041-059-093-119-141-143-149-167-193-211800-  
 
HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
1013 AM CDT THU MAY 22 2008  
 
...ADVANCED HYDROLOGIC PREDICTION SERVICES (AHPS) ENABLE THE  
NATIONAL WEATHER SERVICE TO PROVIDE LONG-RANGE PROBABILISTIC RIVER  
OUTLOOKS...  
 
THIS OUTLOOK IS VALID FROM MAY 26 2008 - AUG 24 2008  
 
THE FOLLOWING TABLE GIVES THE CHANCE OF REACHING FLOOD STAGE AT  
THE GAGES DURING THE VALID PERIOD.  
 
APPROXIMATE CHANCE (%)  
OF REACHING FLOOD LEVEL  
LOCATION FS (FT) MINOR MODERATE MAJOR  
-------- ------- ------------------------  
JAMES RIVER  
HURON SD 11.0 25% 15% < 10%  
FORESTBURG SD 12.0 25% 15% < 10%  
MITCHELL SD 17.0 25% 10% < 10%  
SCOTLAND SD 13.0 20% 15% 10%  
 
FIRESTEEL CREEK  
MT VERNON SD 8.0 15% < 10% < 10%  
 
W FK VERMILLION RIVER  
PARKER SD 9.0 < 10% < 10% < 10%  
 
E FK VERMILLION RIVER  
PARKER SD 12.0 < 10% < 10% < 10%  
 
VERMILLION RIVER  
DAVIS SD 11.0 15% < 10% < 10%  
WAKONDA SD 14.0 20% 15% < 10%  
VERMILLION SD 21.0 < 10% < 10% < 10%  
 
BIG SIOUX RIVER  
BROOKINGS SD 9.0 45% 35% 15%  
DELL RAPIDS SD 12.0 30% 10% < 10%  
S FALLS 60TH ST 12.0 40% 20% < 10%  
SF CLIFF AVE 16.0 25% 15% < 10%  
HAWARDEN IA 15.0 50% 15% < 10%  
AKRON IA 16.0 50% 25% 15%  
SIOUX CITY IA 99.0 < 10% < 10% < 10%  
 
SKUNK CREEK  
SIOUX FALLS SD 11.5 < 10% < 10% < 10%  
 
SPLIT ROCK CREEK  
CORSON SD 8.5 15% < 10% < 10%  
 
ROCK RIVER  
LUVERNE MN 10.0 < 10% < 10% < 10%  
ROCK RAPIDS IA 13.0 15% 10% < 10%  
ROCK VALLEY IA 16.0 10% < 10% < 10%  
 
FLOYD RIVER  
SHELDON IA 12.0 30% 20% < 10%  
ALTON IA 12.0 25% 15% < 10%  
LEMARS IA 20.0 15% 10% < 10%  
STRUBLE IA 14.0 10% < 10% < 10%  
MERRILL IA 12.0 < 10% < 10% < 10%  
JAMES IA 26.0 < 10% < 10% < 10%  
 
PERRY CREEK  
SIOUX CITY IA 24.0 < 10% < 10% < 10%  
 
LITTLE SIOUX RIVER  
SPENCER IA 10.0 60% 15% 10%  
LINN GROVE IA 18.0 45% 20% 15%  
CHEROKEE IA 17.0 35% 15% < 10%  
CORRECTIONVILLE 19.0 25% 20% 10%  
 
WEST FORK DITCH  
HORNICK IA 20.0 25% 15% < 10%  
 
REDWOOD RIVER  
MARSHALL MN 14.0 10% < 10% < 10%  
 
DES MOINES RIVER  
JACKSON MN 12.0 15% < 10% < 10%  
 
IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE THE  
CHANCE THE RIVER COULD RISE ABOVE THE LISTED STAGE LEVELS IN THE  
NEXT 90 DAYS. EXAMPLE: THE JAMES RIVER NEAR SCOTLAND HAS A FLOOD  
STAGE OF 13 FEET. THERE IS A 30 PERCENT CHANCE THAT THE RIVER WILL  
RISE ABOVE 10.5 FEET IN THE NEXT 90 DAYS.  
 
LOCATION FS(FT) 90% 80% 70% 60% 50% 40% 30% 20% 10%  
----------- ---- --- --- --- --- --- --- --- --- ---  
JAMES RIVER  
HURON 11.0 9.3 9.3 9.5 9.7 9.9 10.1 10.4 12.5 14.1  
FORESTBURG 12.0 4.9 5.3 5.5 6.0 6.5 8.1 10.2 12.9 14.3  
MITCHELL 17.0 11.5 11.8 12.1 12.5 13.0 14.4 16.1 17.9 19.8  
SCOTLAND 13.0 5.6 5.7 6.0 6.3 7.3 9.1 10.5 12.0 16.3  
 
FIRESTEEL CREEK  
MOUNT VERNON 8.0 2.9 2.9 2.9 2.9 3.2 4.1 4.9 6.0 8.8  
 
WEST FORK VERMILLION RIVER  
PARKER 9.0 1.7 1.7 1.7 1.7 1.7 1.7 2.4 3.0 4.4  
 
EAST FORK VERMILLION RIVER  
PARKER 12.0 4.5 4.5 4.5 4.7 5.4 6.3 6.8 8.4 10.4  
 
VERMILLION RIVER  
DAVIS 11.0 3.4 3.4 3.5 4.4 6.0 6.7 8.5 10.2 11.7  
WAKONDA 14.0 5.6 5.6 5.9 6.3 6.9 8.3 11.9 14.1 16.6  
VERMILLION 21.0 5.4 5.4 5.9 6.6 7.6 8.7 12.4 14.4 20.1  
 
BIG SIOUX RIVER  
BROOKINGS 9.0 4.8 5.1 6.0 7.5 8.3 9.4 11.4 11.6 12.7  
DELL RAPIDS 12.0 5.9 6.5 7.4 8.2 8.8 10.2 12.3 13.1 14.3  
60TH STREET 12.0 10.2 10.4 10.8 11.2 11.5 12.2 13.2 13.9 15.1  
NORTH CLIFF 16.0 7.7 8.2 9.0 9.7 10.7 12.2 14.1 17.0 20.0  
HAWARDEN 15.0 8.7 9.9 11.8 13.3 15.3 16.3 17.1 18.9 21.9  
AKRON 16.0 10.3 11.3 12.6 14.2 16.4 17.4 17.9 19.5 22.3  
SIOUX CITY 99.0 86.2 86.5 87.0 87.8 89.3 90.0 90.6 92.4 96.0  
 
SKUNK CREEK  
SIOUX FALLS 11.5 4.7 4.7 4.9 5.1 5.6 6.3 6.8 7.2 8.7  
 
SPLIT ROCK CREEK  
CORSON 8.5 2.7 3.4 4.0 4.4 5.0 5.6 6.1 6.9 9.1  
 
ROCK RIVER  
LUVERNE 10.0 4.1 4.2 4.4 4.5 4.8 5.0 5.3 6.4 7.5  
ROCK RAPIDS 13.0 8.6 9.3 9.5 9.9 10.5 11.2 11.8 12.6 17.3  
ROCK VALLEY 16.0 6.1 6.9 7.8 8.2 8.8 9.8 10.6 12.6 16.0  
 
FLOYD RIVER  
SHELDON 12.0 5.6 6.0 7.2 8.1 8.5 10.2 11.9 14.0 14.6  
ALTON 12.0 6.4 6.7 7.9 9.1 9.6 10.6 11.5 13.3 16.5  
LE MARS 20.0 11.5 12.3 13.0 13.9 14.6 15.4 15.9 19.3 21.1  
MERRILL 20.0 1.4 1.7 3.0 3.6 4.4 4.8 5.4 8.1 11.2  
JAMES 26.0 10.8 11.5 12.5 13.1 13.8 14.2 14.9 17.7 20.0  
 
WEST BRANCH FLOYD RIVER  
STRUBLE 14.0 4.7 5.0 5.8 6.8 7.2 8.1 9.1 12.2 13.8  
 
PERRY CREEK  
SIOUX CITY 24.0 7.0 7.4 7.9 8.3 8.5 8.8 9.1 9.5 11.4  
 
LITTLE SIOUX RIVER  
SPENCER 10.0 6.1 7.9 8.8 9.9 10.9 11.9 12.7 13.2 16.0  
LINN GROVE 18.0 16.6 16.8 17.0 17.3 17.6 18.3 18.9 19.5 22.2  
CHEROKEE 17.0 8.3 9.8 10.7 11.7 13.3 14.8 17.4 19.4 22.2  
CORRECTIONVILLE 19.0 6.9 7.4 8.1 9.7 10.5 11.7 14.6 19.9 21.1  
 
WEST FORK DITCH  
HORNICK 20.0 7.0 9.6 10.8 12.1 13.8 16.3 18.4 20.9 23.5  
 
REDWOOD RIVER  
MARSHALL 14.0 8.7 8.7 9.5 9.8 10.3 11.3 12.5 13.1 14.1  
 
DES MOINES RIVER  
JACKSON 12.0 5.3 5.3 5.5 6.2 6.9 8.4 9.8 11.2 13.0  
 
THE NUMBERS CONTAINED IN THIS LONG-RANGE PROBABILISTIC OUTLOOK  
REPRESENT NATURAL FLOWS. THAT IS...FLOWS UNAFFECTED BY MAN-MADE  
STRUCTURES IN THE BASIN SUCH AS DIVERSION DAMS AND RESERVOIRS.  
 
THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS FORECAST VALUES THAT  
ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS  
OF CLIMATOLOGICAL DATA INCLUDING CURRENT CONDITIONS OF THE  
RIVER...SNOW COVER...AND SOIL MOISTURE...AND THE 30 TO 90 DAY  
LONG-RANGE OUTLOOKS OF TEMPERATURE AND PRECIPITATION. BY PROVIDING  
THE COMPLETE RANGE OF PROBABILITIES...THE LEVEL OF RISK ASSOCIATED  
WITH LONG-RANGE PLANNING DECISIONS CAN BE DETERMINED. THESE  
PROBABILISTIC FORECASTS ARE PART OF THE NATIONAL WEATHER SERVICE'S  
ADVANCED HYDROLOGIC PREDICTION SERVICES (AHPS).  
 
LONG-RANGE PROBABILISTIC OUTLOOKS WILL BE ISSUED TOWARD THE END OF  
THE MONTH THROUGHOUT THE YEAR. THE NEXT SCHEDULED OUTLOOK FOR THESE  
SITES WILL BE ISSUED TOWARD THE END OF JUNE 2008.  
 
VISIT OUR WEB SITE AT WWW.WEATHER.GOV/FSD FOR MORE WEATHER AND RIVER  
INFORMATION INCLUDING GRAPHS OF PROBABILISTIC RIVER OUTLOOKS.  
 

 
 
MG  
 
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